Combined Cycle System with a Water Turbine

ABSTRACT

The present application and the resultant patent provide a combined cycle system with a flow of feed water therein. The combined cycle system may include a gas turbine, a steam turbine, a heat exchanger with the flow of feed water flowing therethrough, an expansion source for expanding the flow of feed water, and a supplemental power generation system positioned between the heat exchanger and the expansion source and driven by the flow of feed water.

TECHNICAL FIELD

The present application and the resultant patent relate generally to gas turbine engines and more particularly relate to a combined cycle system using one or more water turbines for supplemental power generation and/or other uses from otherwise wasted energy.

BACKGROUND OF THE INVENTION

Generally described, a combined cycle system uses a combination of a gas turbine and a steam turbine to produce electrical power or otherwise drive a load. Specifically, a gas turbine cycle may be operatively combined with a steam turbine cycle by way of a heat recovery steam generator and the like. The heat recovery steam generator is a heat exchanger that allows feed water for the steam generation process to be heated by the hot combustion gases of the gas turbine exhaust. The primary efficiency of the combined cycle system arrangement is the utilization of the otherwise “wasted” heat of the gas turbine engine exhaust. Specifically, the efficiency of the heat recovery steam generator focuses on the heat transfer between the gas turbine combustion gases (“the hot side”) and the feed water and the steam (“the cold side”). As much of the heat and pressure as possible of the gas turbine combustion gases thus may provide useful work.

Although a combined cycle system is efficient, there are numerous types of parasitic losses involved in overall system operation. For example, high pressure water from the heat recovery steam generator may be used to heat the flow of fuel to the gas turbine engine so as to improve overall turbine performance. This high pressure water, however, generally is dumped directly to the condenser after heating the fuel without utilizing all of the pressure energy therein.

In addition to parasitic loses, a combined cycle system also may have routine operating losses. These losses may be due to equipment design requirements, pressure budgets, and the like. For example, high pressure water in the heat recovery steam generator may be expanded across a number of valves without accomplishing useful work when flowing into a low pressure drum or elsewhere at normal operating flows and pressures.

There is thus a desire for an improved combined cycle power plant with reduced parasitic loses and operating losses. Preferably, otherwise wasted high pressure and/or heat may provide useful work for supplemental power generation and/or other uses.

SUMMARY OF THE INVENTION

The present application and the resultant patent thus provide a combined cycle system with a flow of feed water therein. The combined cycle system may include a gas turbine, a steam turbine, a heat exchanger with the flow of feed water flowing therethrough, an expansion source for expanding the flow of feed water, and a supplemental power generation system positioned between the heat exchanger and the expansion source and driven by the flow of feed water.

The present application and the resultant patent further provide a heat recovery steam generator with a flow of feed water therein. The heat recovery steam generator may include an economizer, a drum, and a water turbine positioned between the economizer and the drum.

The present application and the resultant patent further provide a combined cycle system with a flow of feed water therein. The combined cycle system may include a gas turbine, a performance heater with the flow of feed water flowing therethrough, a steam turbine with a condenser, and a water turbine positioned downstream of the performance heater and driven by the flow of feed water.

These and other features and improvements of the present application and the resultant patent will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematic view of a combined cycle system with a gas turbine engine, a steam turbine, and a heat recovery steam generator.

FIG. 2 is a schematic diagram of a portion of a combined cycle system as may be described herein with a water turbine.

FIG. 3 is a plan view of a water turbine as may be used with the combined cycle system of FIG. 2.

FIG. 4 is a schematic diagram of an alternative embodiment of a combined cycle system as may be described herein.

FIG. 5 is a schematic diagram of an alternative embodiment of a combined cycle system as may be described herein.

DETAILED DESCRIPTION

Referring now to the drawings, in which like numerals refer to like elements throughout the several views, FIG. 1 shows a schematic diagram of a combined cycle system 10. The combined cycle system 10 may include a gas turbine engine 12. The gas turbine engine 12 may include a compressor 14. The compressor 14 compresses an incoming flow of air 16. The compressor 14 delivers the compressed flow of air 16 to a combustor 18. The combustor 18 mixes the compressed flow of air 16 with a pressurized flow of fuel 20 and ignites the mixture to create a flow of combustion gases 22. Although only a single combustor 18 is shown, the gas turbine engine 12 may include any number of combustors 18. The flow of combustion gases 22 is in turn delivered to a turbine 24. The flow of combustion gases 22 drives the turbine 24 so as to produce mechanical work. The mechanical work produced in the turbine 24 drives the compressor 14 via a shaft 26 and an external load 28 such as an electrical generator and the like. The gas turbine engine 12 may use natural gas, various types of syngas, and other types of fuels. The gas turbine engine 12 may have different configurations and may use other types of components.

The combined cycle system 10 also includes a steam turbine 30. The steam turbine 30 may include a high pressure section 32, an intermediate pressure section 34, and one or more low pressure sections 36 with multiple steam admission points at different pressures. The low pressure section 36 may exhaust into a condenser 38. One or multiple shafts 26 may be used herein. Other configurations and other components also may be used herein.

The combined cycle system 10 also may include a heat recovery steam generator 40. The heat recovery steam generator 40 may include a low pressure section 42, an intermediate pressure section 44, and a high pressure section 46. Each section 42, 44, 46 generally includes one or more drums, economizers, evaporators, and/or superheaters. In this example and in addition to other components, the low pressure section 42 may include a low pressure drum 48 and a low pressure economizer 50. Likewise, the intermediate pressure section 44 may include an intermediate pressure drum 52 and an intermediate pressure economizer 54.

Feed water from the condenser 38 may be fed to the heat recovery steam generator 40 via a condensate pump 56. The flow of feed water may be expanded within the low pressure drum 48 and then pass through the sections 42, 44, 46 of the heat recovery steam generator 40 so as to exchange heat with the flow of combustion gases 22 from the gas turbine engine 12. The steam produced in the heat recovery steam generator 40 then may be used to drive the steam turbine 30. Likewise, hot, high pressure water produced in the heat recovery steam generator 40 may be used in a performance heater 58 to heat the incoming flow of fuel 20 to the combustor 18. The water used in the performance heater 58 generally is dumped directly to the condenser 38 after use. This description of the combined cycle system 10 is for the purpose of example only. Many other components and other configurations may be used herein.

FIG. 2 shows portions of a combined cycle system 100 as may be described herein. Specifically, portions of a heat recovery steam generator 110 for use with the combined cycle system 100 are shown. The heat recovery steam generator 110 includes a low pressure section 120 among other components. Similar to that described above, the low pressure section 120 may include an expansion source 130 such as a low pressure drum 135 and a heat exchanger 140 such as a low pressure economizer 145. In normal operation, the flow of feed water may be heated in the low pressure economizer 145 and expanded in the low pressure drum 135. Other component and other configurations may be used herein.

Instead of flowing the feed water from the lower pressure economizer 140 directly to the low pressure drum 130 for expansion therein as is described above, at least a portion of the flow of feed water may be directed to a supplemental power generation system 150. As will be described in more detail below, the supplemental power generation system 150 may include a water turbine 160. The water turbine 160 may be in communication with a by-pass line 170 from the low pressure economizer 140. The flow of feed water then may flow into a splitter 180 with a first portion of the flow heading towards the water turbine 160 via a turbine line 190 and a second portion of the flow heading towards the low pressure drum 130 via a makeup line 200. The turbine line 190 may include one or more flow control valves 210 and/or inlet valves 220. The makeup line 200 may include one or more level control valves 230 and a level controller 240. After passing through the water turbine 160, the first portion of the flow may continue to the low pressure drum 130 via a return line 250. Additional inlet valves 220 and the like may be used herein. Other components and other configurations may be used herein.

FIG. 3 shows an example of the water turbine 160. The water turbine 160 may be in communication with the turbine line 190 via the inlet valve 220. The water turbine 160 may include an inlet reducer 260. The inlet reducer 260 may have a narrowing diameter so as to increase the pressure of the flow. The inlet reducer 260 may lead to a turbine 270 with a number of turbine vanes therein. As the flow expands across the turbine 270, hydraulic energy from the flow is converted into mechanical energy. Specifically, the mechanical energy of the turbine 270 may drive a shaft 280 with the vanes thereon. In turn, the shaft 280 may drive a load 290. In this example, the load 290 may be an induction generator 300 and the like. Generally described, the induction generator 300 operates at grid frequency regardless of the rotational speed. The induction generator 300 thus produces supplemental power for the overall combined cycle system 100. Alternatively, the load 290 may be any device requiring a rotational driving force. For example, the load 290 may be a mechanical device 305 such as a pump, a gear, and the like. The water turbine 160 may be of conventional design. Other components and other configurations may be used herein.

The supplemental power generation system 150 thus uses the pressure of the flow of feed water from the low pressure economizer 145 to drive the water turbine 150. The otherwise wasted pressure in the flow thus drives the induction generator 300 to produce supplemental power or other types of useful work. Multiple supplemental power generation systems 150 and multiple water turbines 160 may be used herein in varying locations.

FIG. 4 shows a further embodiment of a combined cycle system 310 as may be described herein. In this example, a supplemental power generation system 320 may be positioned about an intermediate pressure section 330. In addition to other components, the intermediate pressure section 330 may include the expansion source 130 as an intermediate pressure drum 340 and the heat exchanger 140 as an intermediate pressure economizer 350. A water turbine 360 thus may be positioned between the intermediate pressure economizer 350 and the intermediate pressure drum 340 in a manner similar to that described above. Other components and other configurations may be used herein.

FIG. 5 shows a further embodiment of a combined cycle system 370 as may be described herein. In this example, a supplemental power generation system 380 may be positioned between the heat exchanger 140 as a performance heater 390 and the expansion source 130 as a condenser 400 and/or a condensate pump 410 (and upstream of the low pressure section 120). Specifically, a water turbine 420 may be positioned downstream of the performance heater 390 to take advantage of the high pressure flow therein. Other components and other configurations may be used herein.

The supplemental power generation systems described herein thus utilize otherwise wasted high pressure flows so as to produce supplemental power and/or otherwise useful work in a combined cycle system. The positioning of the water turbine 160 downstream of the low pressure economizer 140, the intermediate pressure economizer 350, and/or the performance pump 390 are for the purpose of example only. The water turbine 160 may be positioned across any pressure drop in any location so as to recover energy therein (although locations with large water flow rates and high pressures may be preferred). The supplemental power generation systems thus improve overall system efficiency and output.

It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof. 

We claim:
 1. A combined cycle system with a flow of feed water therein, comprising: a gas turbine; a steam turbine; a heat exchanger with the flow of feed water flowing therethrough; an expansion source for expanding the flow of feed water; and a supplemental power generation system positioned between the heat exchanger and the expansion source and driven by the flow of feed water.
 2. The combined cycle system of claim 1, wherein the heat exchanger comprises a low pressure economizer.
 3. The combined cycle system of claim 2, wherein the expansion source comprises a low pressure drum.
 4. The combined cycle system of claim 1, wherein the heat exchanger comprises an intermediate pressure economizer.
 5. The combined cycle system of claim 4, wherein the expansion source comprises an intermediate pressure drum.
 6. The combined cycle system of claim 1, wherein the heat exchanger comprises a performance heater.
 7. The combined cycle system of claim 6, wherein the expansion source comprises a condenser.
 8. The combined cycle system of claim 6, wherein the expansion source comprises a condensate pump.
 9. The combined cycle system of claim 1, wherein the supplemental power generation system comprises a water turbine.
 10. The combined cycle system of claim 9, wherein the water turbine comprises an inlet reducer.
 11. The combined cycle system of claim 9, wherein the water turbine drives a load.
 12. The combined cycle system of claim 11, wherein the load comprises an induction generator.
 13. The combined cycle system of claim 9, wherein the load comprises a mechanical device.
 14. A heat recovery steam generator with a flow of feed water therein, comprising: an economizer; a drum; and a water turbine positioned between the economizer and the drum.
 15. The heat recovery steam generator of claim 14, wherein the economizer comprises a low pressure economizer and the drum comprises a low pressure drum.
 16. The heat recovery steam generator of claim 14, wherein the economizer comprises an intermediate pressure economizer and the drum comprises an intermediate pressure drum.
 17. The heat recovery steam generator of claim 14, wherein the water turbine comprises an inlet reducer.
 18. The heat recovery steam generator of claim 14, wherein the water turbine comprises an induction generator.
 19. The heat recovery steam generator of claim 14, wherein the water turbine comprises a mechanical device.
 20. A combined cycle system with a flow of feed water therein, comprising: a gas turbine; a performance heater with the flow of feed water flowing therethrough; a steam turbine; the steam turbine comprising a condenser; and a water turbine positioned downstream of the performance heater and driven by the flow of feed water. 